Chapter 122. Acute Infectious Diarrheal Diseases and Bacterial Food Poisoning (Part 6) pptx

Chapter 122. Acute Infectious Diarrheal Diseases
and Bacterial Food Poisoning
(Part 6)
Table 122-3 Epidemiology of Traveler's Diarrhea

Etiologic Agent Approximate
Percentage of Cases
Comments
Enterotoxigenic
Escherichia coli
15–50 Single most importan
t
agent, particularly in
summertime in semitropical
areas; percentage of cases
ranges from 15% in Asia to
50% in Latin America
Enteroaggregative
E. coli
20–35
Emerging enteric
pathogen of worldwide
distribution
Shigella
and
enteroinvasive E. coli
10–25
Major causes of fever
and dysentery
Salmonella 5–10
Causes fever and

dysentery
Campylobacter
jejuni

3–15
More common in winter
in semitropical areas; more
common in Asia
Aeromonas 5 Important in Thailand
Plesiomonas 5
Related to tropical travel
and seafood consumption
Vibrio cholerae 0–10
Most common in India
and Asia; also common in
Central and South America
Rotavirus and
10–40
Latin America, Asia,
and Africa; norovirus
norovirus
associated with seafood
ingestion on cruise ships
Entamoeba
histolytica
5
Particularly important in
Mexico and Thailand
Giardia lamblia <2
Zoonotic reservoirs in

northern United States; affects
hikers and campers who drink
from freshwater streams;
contaminates water supplies in
Russia
Cryptosporidium 2 Affects tr
avelers to
Russia, Mexico, and Africa;
causes large-
scale urban
outbreaks in United States
Cyclospora <1
Affects travelers to
Nepal, Haiti, and Peru;
contaminates water or food
Unknown 20
Illness improves with
antibacterial therapy,
implicating bacterial diarrhea

Source: After Dupont.
Location
Day-care centers have particularly high attack rates of enteric infections.
Rotavirus is most common among children <2 years old, with attack rates of 75–
100% among those exposed. G. lamblia is more common among older children,
with somewhat lower attack rates. Other common organisms, often spread by
fecal-oral contact, are Shigella, Campylobacter jejuni, and Cryptosporidium. A
characteristic feature of infection among children attending day-care centers is the
high rate of secondary cases among family members.
Similarly, hospitals are sites in which enteric infections are concentrated. In

medical intensive-care units and pediatric wards, diarrhea is one of the most
common manifestations of nosocomial infections. C. difficile is the predominant
cause of nosocomial diarrhea among adults in the United States. Viral pathogens,
especially rotavirus, can spread rapidly in pediatric wards. Enteropathogenic E.
coli has been associated with outbreaks of diarrhea in nurseries for newborns.
One-third of elderly patients in chronic-care institutions develop a significant
diarrheal illness each year; more than half of these cases are caused by cytotoxin-
producing C. difficile. Antimicrobial therapy can predispose to
pseudomembranous colitis by altering the normal colonic flora and allowing the
multiplication of C. difficile (Chap. 123).